function rel() {
	var model = document.form_4.model.value;
	var i;
	var ch = "";
	var ch2 = document.form_4.s.value;
	for (i = 0; i < document.form_4.t.length; i++) {
		if (document.form_4.t[i].checked) {
			ch = document.form_4.t[i].value + " " + ch;
		}
	}

	var xhr = null;

	if (ch == "" || ch2 == "")
		alert("ERREUR : Selection!!");
	else {
		if (window.XMLHttpRequest) {
			xhr = new XMLHttpRequest();
		} else if (window.ActiveXObject) {
			xhr = new ActiveXObject("Microsoft.XMLHTTP");
		}
		xhr.open("GET", "Select2_query.jsp?ch=" + ch + "&ch2=" + ch2
				+ "&model=" + model, false);
		xhr.send(null);

		document.getElementById("rst").innerHTML = xhr.responseText;
	}
}